Alkaline hydrolysis resistant adhesive

ABSTRACT

There is described herewith an alkaline hydrolysis resistant carpet adhesive comprising an n-butyl acrylate acrylic polymer.

TECHNICAL FIELD

The present invention relates to an alkaline hydrolysis resistantadhesive. In one embodiment the present invention relates to an alkalinehydrolysis resistant adhesive suitable for securing a laminated floorcovering such as a carpet or carpet tile to a surface having a high pH.

BACKGROUND OF THE INVENTION

Carpets, such as free-lay carpet or backed carpet tiles are typicallyprepared as either a tufted or a fusion bonded carpet material having awear fibrous or pile surface from which pile yarns upwardly project.Carpet tiles differ from the production of ordinary tufted or otherfibrous-faced carpets because there is no requirement on a typicalcarpet for a heavy backing layer. In a carpet tile, a rigid stabilizedmass of a thermoplastic backing layer is typically required in order tohold down the carpet tile so that it can function as a free-lay carpettile. Generally, the backing layer has a high filler content (e.g.,limestone) and is employed with various scrim materials such as glassfibres, polyester or a combinations thereof, to impart dimensionalstability. Generally the thermoplastic backing layer is one or morepolyvinyl chloride layers.

As an example, a tufted carpet tile generally comprises a primarybacking base sheet material such as polyester or polypropylene having aplurality of tufted yams such as Nylon® through the primary backing toform a wear surface of loop or cut pile (carpet pile). The primarybacking is used to tuft the carpet yarn into and to provide the requiredtop cloth of the product. A precoat of a latex type material such as EVA(polyethylene vinyl acetate) or carboxylated styrene-butadiene-styrenemay be applied on the back (underside) surface to bond the yam to theprimary backing and to aid in the securing of the primary backing to thebacking layer. The backing layer may be comprised of a first PVC layer,a fiberglass layer and a second PVC layer (reback layer)—the first layerof PVC bonding the primary backing to the fiberglass layer, thefiberglass layer ensuring dimensional stability of the carpet tile andthe second layer of PVC gluing the layers above it and providing thefinal backing of the carpet tile.

In an alternative construction of the above carpet tiles, the PVC layeris replaced with a bitumen layer.

Fusion-bonded carpet generally has a similar backing to tufted carpetexcept that the fusion-bonded carpet has a plurality of cut pile yams ofnylon or other suitable fibrous material implanted in an adhesive layer,particularly a thermoplastic such as PVC or hot-melt adhesive, which maybe further laminated to a reinforcement or substrate layer of a woven ornon-woven material such as fibreglass, Nylon®, polypropylene orpolyester. The plurality of fibrous yams are bonded to and extendgenerally upright from the adhesive base layer to form the wear surface.

Carpets have many applications as a floor covering for various surfacesincluding wood and concrete. Typically carpets are installed by applyingan adhesive to the surface such as concrete, suitably as a thin filmfollowed by positioning of the carpet on top of the adhesive and curingof the adhesive to thereby form a bond between the surface and thecarpet. Alternatively, the adhesive may be applied directly to theunderside of the carpet and a releasable film provided which is removedprior to use. It has been found however that with conventional pressuresensitive acrylic adhesives and where the surface has a pH of above 9and a high moisture content, conventional adhesives break down formingexcessive volatile organic compounds, such as 2-ethyl-1-hexanol,alcohols and esters. This occurs particularly where the time frompouring the concrete surface to installation of the carpet is short andwhere the concrete slab has not had sufficient time to settle and fullycure. It has been found that in these conditions all the adhesive may berequired to be removed or the surface sealed prior to application whichmay be undesirable.

Object of the Invention

It is an object of the present invention to substantially overcome or atleast ameliorate one or more of the above disadvantages or at leastprovide a suitable alternative.

DEFINITIONS

The following are some definitions that may be helpful in understandingthe description of the present invention. These are intended as generaldefinitions and should in no way limit the scope of the presentinvention to those terms alone, but are put forth for a betterunderstanding of the following description.

Unless the context requires otherwise or specifically stated to thecontrary, integers, steps, or elements of the invention recited hereinas singular integers, steps or elements clearly encompass both singularand plural forms of the recited integers, steps or elements.

Throughout this specification, unless the context requires otherwise,the word “comprise”, or variations such as “comprises” or “comprising”,will be understood to imply the inclusion of a stated step or element orinteger or group of steps or elements or integers, but not the exclusionof any other step or element or integer or group of elements orintegers. Thus, in the context of this specification, the term“comprising” means “including principally, but not necessarily solely”.

The information provided herein and references cited are provided solelyto assist the understanding of the reader, and do not constitute anadmission that any of the references or information is prior art to thepresent invention.

The term “filament” or “filaments” means strands of extreme orindefinite length.

The term “yarn” means a collection of numerous filaments which may ormay not be entangled, twisted or laid together.

The term “textured” or “texturing” means any operation of filamentswhich results in crimping, looping or otherwise modifying such filamentsto increase cover, resilience, bulk or to provide a different surfacetexture or hand. It follows that a “bulked continuous filament” is afilament which has been subjected to one or more “texturing”operation(s).

By “biobased” is meant that the relevant material is made fromsubstances derived from living matter.

It will be understood that although the description of the carpet orcarpet tile of the present invention has been given in terms of“layers”, that following processing the carpet tile is a bonded unitaryintegral structure in which the individual layers are not necessarilyreadily discernible or removable from one another.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is providedan alkaline hydrolysis resistant carpet adhesive comprising an n-butylacrylate acrylic polymer.

According to a second aspect of the present invention, there is provideda method of positioning a carpet on a surface comprising:

forming a film of the adhesive of the first aspect on the surface orapplying the adhesive to an underside of the carpet,

positioning the carpet on the surface; and

allowing the adhesive to cure to thereby from a releasable bond betweenthe carpet and the surface.

According to a third aspect of the present invention, there is provideda carpet having an adhesive according to the first aspect applied to anunderside of the carpet and a releasable protective layer attached tothe adhesive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has been discovered that in the presence of a high pH (above about pH9) and in high moisture environments (for example above 5 wt %), forexample on green slabs, conventional carpet adhesives breakdown forminghigh volatile compounds such as 2-ethyl-1-hexanol. Even at pH 9 theadhesive may begin to breakdown up to a year after installation of thecarpet. Such volatile compounds are typically pungent and can causenausea, headaches and vomiting. It was originally thought that thepresence of such high volatile compounds was a result of the PVC backinggenerally used in carpets however this is not the case and it has beenfound that it is a function of a reaction occurring in the adhesiveitself as a result of the high pH and moist environment. This was notexpected. Volatile Organic Content (VOC) emissions of 2800 μg/m²/h havebeen measured using conventional adhesives.

The present invention relates to an alkaline hydrolysis resistant carpetadhesive comprising an n-butyl acrylate acrylic polymer. The n-butylacrylate acrylic polymer is suitably an aqueous dispersion of athermoplastic acrylic polymer based on n-butylacrylate having a totalsolids content of about 60% and having a glass transition temperature ofabout −42° C.

The adhesive may be in an aqueous formulation.

The butyl acrylate acrylic polymer may be combined with any crosslinkedacrylic polymer. For example the polymer may be combined with an APEO(alkyl phenol ethoxylate) free acid-containing acrylic emulsioncopolymer.

In one embodiment the adhesive has a total solids content suitably inthe range of 44 to 46 wt %.

The adhesive may include additional additives such as fillers,thickeners, defoamers, antimicrobials, fungicides, biocides, pHadjusters/neutralising agents, tackifiers, surfactants, rheologymodifiers, wetting agents, polymer blends and mixtures thereof.

Suitable fillers may include calcium carbonate, barium sulphate, zincoxide, aluminium hydrate, titanium dioxide, lime, clays, recycled glass,ash or mixtures thereof. Fillers may be used in amounts up to 5 wt % butin an amount not affecting surface tack properties.

Suitably thickeners may include acrylic copolymers, alkali swellablethickeners, sodium polyacrylate, cellulosic thickeners and mixturesthereof. The thickeners may be included in amounts up to 10 wt %, forexample 2 to 10 wt %.

Suitable defoamers include oil based defoamers such as oil based withoutsilicone defoamers. The defoamers may be used in amounts up to 0.2 wt %for example 0.1-0.2wt %.

Suitable pH adjusters/neutralising agents include sodium hydroxide,potassium hydroxide or ammonia. Amounts used will depend on the desiredpH of the final formulation. In one embodiment the adhesive has a pH offrom 7 to 10, for example 7 to 9.

Suitable biocides include zinc omadine and MIT/BIT biocide (a 5% equalblend of 2-methyl-2H-isothiazol-3-one/1,2-benzisothiazol-3(2H)-one).Other biocides may be used. The biocide may be used in amounts up to 0.3wt %, for example 0.1-0.3 wt %.

Suitably the adhesive has a viscosity within the range of 2000 cps to50000 cps. For rollable viscosity suitably should be 2,000 cps minimumand trowellable viscosity minimum suitably 10,000 cps. For example theviscosity may be 15000 to 17000cps stirred (RVT 6/10).

The adhesive may have a density of 0.95 to 1.15 g/cm³ at 20° C., forexample 0.95 to 1.05 g/cm³.

The present invention also relates to a method of positioning a carpeton a surface comprising:

forming a film of the adhesive of the first aspect on the surface orapplying the adhesive to an underside of the carpet,

positioning the carpet on the surface; and

allowing the adhesive to cure to thereby from a releasable bond betweenthe carpet and the surface.

The surface may be concrete or timber and may include a sealer or anepoxy coating on the surface. Sealers should suitably be of an acrylicor similar type and not contain waxes or any chemicals that will affectwetting of the adhesive.

The surface may have a pH of above 9. In one embodiment the surface mayhave a pH above 10. In another embodiment the surface may have a pHabove 11. In another embodiment the surface may have a pH above 12.

The surface may have a moisture content of 5wt % or above.

Carpet

In one embodiment the carpet includes a primary backing having a fibrousface and an underside, wherein the fibrous face is formed from yamtufted or implanted into the primary backing. The carpet mayadditionally include a cured precoat layer on the underside of theprimary backing and a backing layer fixed to the primary backing.

The primary backing may be a tufted fibrous layer or a fusion bondedmaterial. When a tufted fibrous layer is used, it may be prepared byfeeding the primary backing material to a conventional tufting machinewhich tufts fibres through interstices in the material. Tufting istypically performed such that the resulting tufts protrude from theunderside face with back stitches which hold the tufts in place on thetopside of the material during processing.

The primary backing is suitably formed from a woven or non-wovensynthetic or non-synthetic fibre. Suitably a thermoplastic backing suchas a woven polypropylene backing or a non-woven polyester, with afibrous face or wear surface such as a tufted face, and a fibrous backsurface, such as a loop or tufted surface where the carpet tile istufted is used. A polyester such as Lutradur® is preferably used whenmaking a PVC backed floor covering because it does not suffer too muchfrom shrinkage due to heat during the gelling process, thus minimizingthe risk of tile uplift due to not enough drape. Other suitable backingsinclude Nylon®, fibreglass, cotton, jute, rayon, paper, natural orsynthetic rubbers, sponge or foam rubbers, polychloroprene,acrylonitrile-butadiene copolymers, ethylene-propylene-diene rubbers,petroleum resin, vinyl polymers (such as polyvinylchloride,polyvinylidene chloride, polyvinyl acetate, polyvinyl acetal, polyvinylbutyral, copolymers or mixtures thereof), polybutene resin,polyisobutene-butadiene resins and copolymers and mixtures thereof.

The yarn may be any suitable yarn or fibrous material that can be tuftedof implanted into the primary backing. Suitable fibrous materials andyarns may include synthetic, natural or a combination of synthetic andnatural fibre, such as but not limited to polyamides like nylon, olefinslike polypropylene, wool and wool blends, cotton, acrylic, acrylic-nylonblends, polyester yarns, biobased yarns and combinations and blendsthereof. The yams/fibrous materials may be used to form face or backyarn with the primary backing. The yarns may be dyed and may betextured.

For a fusion bonded carpet tile, the fibrous material and yarns employedin the carpet tile are implanted into a material such as PVC or a hotmelt adhesive which may be laminated to a substrate, such as a woven ornonwoven material, such as fibreglass, Nylon®, polypropylene orpolyester.

The primary backing layer may be precoated with latex or with anothersuitable precoating composition of the invention prior to applying abacking layer. Typically the precoat is applied to cover the loop backsand to lock in the loops.

The latex may be an EVA latex or another vinyl polymer or acrylic-likepolymer latex. For example, the latex may be a copolymer of acrylic andmethacrylic acid and alkyl acrylates and esters (such as ethyl acrylateor methyl acrylate), acrylic-styrene copolymers, acrylonitrile-styrenecopolymers, vinylidene chloride-acrylonitrile copolymers, andcombinations thereof. Suitably the latex is non-halogenated. Othersuitable latex materials which can be used include other vinyl,short-chain carboxylic acid copolymers, butadiene-acrylonitrilecopolymer, styrene-butadiene, carboxylated styrene-butadiene orcarboxylated styrene-butadiene-styrene. Urethane, PVC, acrylics orvinylidine chloride may also be used.

The precoating composition/latex may further comprise a thickener, anantibacterial, a fire retardant and/or a surfactant. A suitableantibacterial is zinc omadine—zinc2-pyridinethiol-1-oxide. A suitablefire retardant is aluminium hydroxide. A suitable surfactant is sodiumlauryl sulphate.

In one embodiment a precoating composition is used comprising: at leastone copolymer derived from an acrylic or methacrylic monomer and astyrenic monomer; at least one copolymer derived from an acrylic esterand a methacrylic ester; at least one thickener; and water. Thecopolymer derived from an acrylic or methacrylic monomer and a styrenicmonomer is suitably an acrylate/styrene copolymer dispersion such asthat supplied by BASF Corporation as Acronal® S 728 na. The precoatingcomposition may also contain a copolymer derived from an acrylic esterand a methacrylic ester. This copolymer facilitates the acrylic styrenesticking to thermoplastic materials such as PVC suitably used in themanufacture of the floor coverings. A suitable polymer is Acronal® AX8281 AP available from BASF Aktiengesellschaft. Suitably the thickeneris a thickener suitable for polymer dispersions, for example, an acryliccopolymer containing carboxyl groups. A suitable thickener is Latekoll®D available from BASF Aktiengesellschaft and is a low-viscosity, milkywhite anionic dispersion. The thickener helps to prevent the precoatingcomposition from wicking down holes in the primary backing layer. Thethickener is suitably pre-diluted with water to form a homogeneoussolution prior to the addition to the resins.

The latex/precoating composition can be applied to the primary backingby roller coating, spraying or by foaming. The latex/precoatingcomposition serves to lock in the fibre on the back of the primary, suchas a tufted back layer and acts as a barrier, separating the fibrouscarpet from the underlying backing. The pre-coating is suitably heatedto drive off sufficient water to provide a solid barrier and to allowfor possible cross-linking.

The precoating layer has a thickness which is typically quite thin.Suitably the thickness is about 0.005 mm to 0.1 mm when dry. Thethickness is suitably controlled by the use of spray nozzles and spraypressure. The precoating layer is suitably placed directly on andagainst the back surface of the loop or fibre containing primary backingand is suitably applied in an amount to cover completely the loop backsand to lock in loops so that no mountains or valleys are evident. Duringprocessing the copolymers are suitably cured and crosslinked. Theresulting precoated product is very flexible.

The floor covering may include a backing layer which imparts stabilityand free-laying properties to the floor covering.

Prior to applying the backing layer, it is possible to shear the carpetfibres if desired. Shearing is performed to cut the closed loop, tuftedyam on the face surface and to provide for the cut, tufted yarn to havethe same general height as the height of the face wear surface fibres.

The backing layer may be formed from one or more layers of athermoplastic polymer or other suitable backing material such asdescribed above for the primary backing. In one embodiment thethermoplastic is a vinyl halide. A suitable vinyl halide is PVC(polyvinylchloride). Other suitable backings include bitumen, atacticpolypropylene, polyolefin, ethylene vinyl acetate copolymer,thermoplastic elastomers, polyurethanes, PVC/Latex, bitumen backed latexand polyurethane, polyamines, jute, urethane, polyvinylidine chloride,polyvinyl acetate, polyvinyl butyral, natural or synthetic rubber orpolychloroprene. The backing layer may be in the form of a foam, spongeor solid. When in the form of a foam, the backing layer adds resilienceand/or stability.

The backing layer can have a range of properties depending on the natureof polymers, plasticizers, stabilizers and fillers used. Suitablefillers include recycled glass, limestone or a combination thereof. Theplasticizer may be a standard phthalate plasticizer such as DINP, DEHP,DOP, PEG 100, or PEG 200. A particularly preferred plasticizer is thecombination of epoxide soybean oil and a castor oil derivative. Aviscosity modifier such as an alcohol may be present as required tolower viscosity. A suitable viscosity modifier is ethanol. A suitablesoybean plasticizer is an epoxidised soya bean oil such as LankroflexE2307 (ESBO) AG available from Swift and Company Limited, 372 WellingtonRoad, Mulgrave, Victoria 3170, Australia. The castor oil is derivativeis suitably an acetic acid ester of monoglycerides made from fullyhydrogenated castor oil such as Grindsted® Soft-n-Safe/C available fromDanisco Emulsifiers.

A preferred backing layer is formed from a composition comprisingrecycled glass and the soybean oil/castor oil combination. This resultis a more renewable and less fossil based product. In such a combinationthe composition may include up to about 60% thermoplastic (fossilorigin)

The primary backing and backing layer or latex/precoating compositionmay include any one or more of flame or fire retardants, inert fillerssuch as limestone or barytes, calcium oxide, carbon-black,antibacterials, surfactants, defoamers, thickeners, dispersing agents,elastomers, antioxidants, colourants, hardeners, plasticizers, UV/heatstabilizers, viscosity modifiers, cross-linking agents and/ortackifiers.

The use of a plasticizer in combination with the thermoplastic resinprovides the required flexibility, durability and hardness. The presenceof a heat stabilizer stabilizes the thermoplastic and prevents thermaldecomposition, a UV stabilizer stabilizes the thermoplastic preventingdecomposition as a result of exposure to UV light, calcium oxide ensuresany moisture is removed from the mixing process, calcium carbonate(limestone) acts as filler, increasing the volume of the thermoplasticcompound mix at reduced cost and a viscosity modifier maintainsviscosity to ensure that the mix remains well mixed and in suspension(slowing the dropping out of solids).

The floor covering may include one or more woven or non-woven layers ofglass, fibreglass, polyester, Nylon® or polypropylene such as tissue,mesh, fleece or scrim sheet materials or a combination thereof in theprimary backing and backing layer. The scrim material may be employedadjacent to the primary backing or closely adjacent thereto. Glass fibreor tissue materials may be employed within the thermoplastic backinglayer to impart dimensional stability and improve laying properties ofthe carpet tile. Cushion layers for example, formed of foam may also beincluded.

The floor covering may be prepared in any suitable manner. For example,a layer of thermoplastic may be applied/cast in a defined thickness ontothe underside of the primary backing layer as a wet plastisol. Thecoated material is suitably leveled with a doctor blade which levels andsmooths the thermoplastic layer and forces the thermoplastic layer intoengagement with any glass scrim and the primary backing.

Alternatively, the backing layer may be preformed on a releasablesupport such as a fluorocarbon, glass fibre endless belt, Teflon® coatedfibreglass belt or stainless steel support sheet through casting. Theprecoated primary backing layer is then laid into the liquid backinglayer.

Following application of the backing layer, the carpet is suitablyheated to fuse/gel and cure the thermoplastic, cooled and optionally cutinto carpet tile sections. Heating may be by use of a heater, radiantpanels or heating elements. The heating cures the thermoplastic materialand for a tufted carpet, thereby locks back stitches in place, theprimary backing is thereby bonded to the backing layer by fibres of theprimary backing being embedded in the backing layer. The carpet tile maybe heated to a curing temperature within the range of 50° C. to 170° C.,for example 90° C. to 160° C., 100° C. to 150° C. or 140° C. to 150° C.For example, for PVC, the plasticizer melts and begins diffusing intoparticles at 50° C., gelation begins at about 50° C. and continues toabout 130° C., at which point the particles swell and between 130° C.and 170° C. the gelation stage ends. At 91° C. the polymer flows into acontinuous mass.

A suitable apparatus for finishing the carpet tile may be an apparatusincluding a heater having a chamber to operate at a desired temperatureand through which the primary backing and backing layers pass to beheated to provide for plastic deformation of the backing layer; a pairof press rollers to which the primary backing, backing and anyadditional cushion layers are delivered, after the primary and backinglayers have been heated by the heater, to apply a force thereto to causethe layers to bond, and a controller operatively associated with theheater, the controller being configured to maintain the temperaturewithin the chamber to provide for heating of the backing layer so thatthe backing layer is relatively deformed by the rollers to bond thelayers.

During gelling or after gelling the carpet may be passed under anembossing roller which embosses the back of the carpet withindentations, corrugations or the like to form a friction-increasingsurface (resisting movement and maintaining position when placed insitu) and assists in consolidating the layers into a unitary product.The consolidated carpet material may then be severed by suitable cuttingmeans into appropriate length sections (for example into squares). Thelaminated construction may be cooled for example to about 105° C. toallow removal of the construction from the support. The construction maythen be passed through a heater and raised to about 100° C. prior tobeing engaged by an embossing roller that embosses the thermoplasticlayer.

In one embodiment, the backing layer is formed of a layer ofthermoplastic such as PVC, a fibreglass scrim and a second thermoplasticlayer such as. PVC. The first layer of thermoplastic bonds the primarybacking to the fibreglass layer, the thickness of the layer suitablybeing controlled by a doctor blade. The fibreglass layer is to ensuredimensional stability of the carpet tile. The second layer ofthermoplastic glues the layers above it and provides the final backingof the carpet tile. The thickness of this layer is also suitablycontrolled by a doctor blade.

The backing layer may be applied to the primary backing in a continuousfashion to produce an indeterminate length of material which may besubsequently cut as desired to form the carpet tile.

The thickness of each layer may vary depending on whether a solid layeror foam layer is used. For example, the first PVC layer range isdependant on the weight of the PVC backing i.e., 2.64 kg/m² would be twolayers of 0.88 mm, 2 kg/m² would be two layers at 0.67 mm, while 1.5kg/m² would be two layers at 0.5 mm. The overall carpet thickness maysuitably be between about 4 and 12 mm, for example about 6 mm withoutfoam backing and about 10 mm with foam backing. The resulting floorcovering is suitable for use as a floor covering for home and/orcommercial use.

Installation of the Carpet

In one embodiment, the underside of the carpet may be provided with anadhesive of the invention with a strippable protective layer attachedthereto, where, in use the protective layer is stripped off and thefloor covering applied to the floor surface and the adhesive allowed tocure. In another embodiment the adhesive of the invention is applieddirectly to the surface followed by positioning the carpet over thesurface and allowing the adhesive to cure. The adhesive of the inventionis suitably applied to the substrate suitably using a trowel. Theadhesive has sufficient tack, peel strength and shear strength tomaintain the tile against the floor during use but also allows carpettiles to be replaced or rotated as desired. Volatile organic compoundemissions may be reduced to 50 μg/m²/h which may be further. reducedover time and balances at ambient VOC levels.

The present invention will now be described with reference to thefollowing examples which should not be construed as limiting on thepresent invention.

EXAMPLES Example 1

An adhesive was prepared using the formulation as shown in the followingTable:

Component Amount (100 wt %) n-butylacrylate acrylic polymer 78.4 (Tg -42° C.) Water 14.4 48% zinc omadine 0.2 5% MIT/BIT biocide 0.3 Oil baseddefoamer 0.17 46% sodium hydroxide 0.07 14% alkali swellable thickener6.4 Green pigment 0.06

The adhesive was prepared by adding the acrylic polymer to water in asuitable mixing vessel and stirring the mixture whilst adding the zincomadine, biocide and defoamer in given water. 0.7 wt % water and thesodium hydroxide were premixed and then added slowly to the mix followedby the alkali swellable thickener and the mixture stirred until smoothand uniform. The green pigment was added until fully dispersed, theresulting adhesive quality checked and passed through a 10 mesh filter.

The resulting adhesive had a viscosity of 15000 to 17000 (using aBrookfield Viscosity RVT spindle 5 at 20 rpm at 25° C.) and total solidscontent of 44 to 46%. The pH of the formulation was 7.0 to 9.0 with adensity (specific gravity) of 0.95 to 1.05 g/cm³. The adhesive was apressure sensitive adhesive with low tack.

Example 2

A study was undertaken to compare the emission rate of volatile organiccompounds (2-ethyl-1-hexanol) using the adhesive of the inventioncompared with two commercial adhesives at pH 9, 10 and 11.

Four concrete core samples had the adhesive applied to the flat surfaceand these were placed separately into dishes containing water as acontrol, and water and CaOH at pH 9, 10 11. Each sample remained in thiscondition for four weeks while VOC monitoring was conducted throughoutthe period.

The results are shown in the following table:

pH condition Adhesive Control pH 9 pH 10 pH 11 R656 Pressure 8.2 1 12 14Sensitive Adhesive (supplied by Intertac) Ardex DPF0308 20 21 23 22(supplied by Ardex) Adhesive of <1 <1 <1 <1 Example 1

It can be seen from the table that the adhesive of the invention did notproduce any emissions of 2-ethyl-1-hexanol whereas the conventionaladhesives did produce 2-ethyl-1-hexanol in significant amounts. It wasnoted that the adhesive of Example 1 did give off some propanol in thefirst 15 minutes but this would not affect application of the carpettile which is usually applied 15 to 20 minutes after the adhesive.

Example 3

The adhesive prepared in Example 1 was applied as a thin film to aconcrete surface having a pH of 12 using a V1 or V2 notch trowel. Acarpet tile was positioned on the adhesive and allowed to cure. Nopungent odour was detected and the adhesive has sufficient shearstrength and tack to maintain the carpet against the surface but waspeelable from the surface.

Example 4

Samples of various conventional pressure sensitive adhesivesmanufactured in Australia, Europe and the US were obtained. 200 ml ofeach were decanted into separate sealed containers and 50 ml of CaOHsolution (pH11) was added to each. After 2 hours all of the samplesdisplayed evidence of depolymerisation and all samples producedundesirable VOC's. It was determined at this point that furtherqualitative testing was required. Samples of Intertac pressure sensitiveadhesive was supplied to CETEC Laboratories, to repeat the test andmeasure VOC. Preliminary results showed emission rates while theadhesive was undergoing an alkaline hydrolysis reaction of 2800ugm/m2/hr.

While the invention has been described with respect to a preferredembodiment, it will be understood that the invention is not limited tothe preferred embodiment but is intended to cover various modificationsand equivalent arrangements within the spirit and scope of the appendedclaims.

1-15. (canceled)
 16. A method of positioning a carpet on a surfacecomprising: forming a film of an alkaline hydrolysis resistant carpetadhesive comprising an n-butyl acrylate acrylic polymer on the surfaceor applying the adhesive to an underside of the carpet, wherein thesurface has a pH above 9, positioning the carpet on the surface; andallowing the adhesive to cure to thereby form a releasable bond betweenthe carpet and the surface.
 17. The method of claim 16, wherein then-butyl acrylate acrylic polymer is an aqueous dispersion of athermoplastic acrylic polymer based on n-butylacrylate having a totalsolids content of about 60% and having a glass transition temperature ofabout −42° C.
 18. The method of claim 16, wherein the adhesive is in anaqueous formulation.
 19. The method of claim 16, wherein the n-butylacrylate acrylic polymer is combined with a crosslinked acrylic polymer.20. The method of claim 19, wherein the n-butyl acrylate acrylic polymeris combined with an APEO (alkyl phenol ethoxylate) free acid-containingacrylic emulsion copolymer.
 21. The method of claim 16, wherein theadhesive has a total solids content in the range of 44 to 46wt %. 22.The method of claim 16, wherein the adhesive further comprises additivesselected from fillers, thickeners, defoamers, antimicrobials,fungicides, biocides, pH adjusters/neutralising agents, tackifiers,surfactants, rheology modifiers, wetting agents, polymer blends andmixtures thereof.
 23. The method of claim 16, wherein the adhesive has apH of from 7 to
 10. 24. The method of claim 16, wherein the adhesive hasa viscosity within the range of 2000 cps to 50000 cps.
 25. The method ofclaim 16, wherein the adhesive has a density of 0.85 to 1.15g/cm³ at 20°C.
 26. The method of claim 16, wherein the surface is concrete ortimber.
 27. The method of claim 16, wherein the surface includes asealer or an epoxy coating.
 28. The method of claim 16, wherein thesurface has a pH above about
 10. 29. The method of claim 16, wherein thesurface has a moisture content of 5 wt % or above.
 30. The method ofclaim 16, wherein the adhesive is applied to an underside of the carpetand a releasable protective layer is attached to the adhesive which isremoved prior to positioning.
 31. The method of claim 16, wherein theadhesive has a density of 0.95 to 1.15 g/cm³ at 20° C.